Drill bits for drilling steel

[turftech 1]

Hi all,
I am doing more and more metal work, but I have yet to find a good way of drilling larger bore holes in steel. I have a 1/2" and a 5/8" bit, but they dull out almost instantly. I sharpen them on my bench grinder, but they just don't hold up.

So, what do you use to drill larger holes (say 3/8" and up) in steel? Are there certain brands or types that hold up better? I have tried step-drill bits and those dull out quickly too.

Anyone tried using those drill bit sharpeners?

 

[Beal]

Ive heard that drill bits for ceramic work good for metal...

Are what your using for metal? If not that could be your problem...
:shrug:

 

[texasfabguy]

carbide bits,slow down the speed. The bigger the size the slower you go. adjust the bit pressure and speed buy how much chips are being produced. I still sharpen my bits by hand but I have had a Drill Doctor at one time and some swear by them.

 

[gbabins1]

I'm no expert by any means... but I find if I keep them lubed up while I'm drilling it prolongs the life of the bit.

 

[Square_Chopper]

carbide bits,slow down the speed. The bigger the size the slower you go.

These three things are key! :thumbsup:

 

[hemigremmy]

Slower drill speed, don't put all your weight on the drill bit just good steady pressure, and cutting OIL. I have drilled 9/16" diameter holes in 3/8" thick plate with a hand drill and a bit from Sears and oil. It took a long time to drill 8 holes but worked great.

 

[oldsledz]

I start with a small bit and work my way up, dip the tip in oil, more to keep it cool than for lube. Don't let the bit get hot the heat is vary hard on a bit.

 

[jeep2003]

i have a drill doctor but i dont use it anymore its faster and easier to just bench grind them. work your way up in size and keep it cool. i keep a spray bottle of water on the bench all the time for keeping bits and stuff cool. a standard 3/8" drill spins alot faster than a 1/2" drill. as i get up in size i switch to the bigger drill. its easier on the small drill and spins slower. I have about 1000 drill bits in a bin that i just pick from. I almost never throw any away they can be cut off if you totally roast the tip and sharpened again. Also masonry bits work quite well in metal and they can be sharpend too. but eventually the tips break off then theyre junk

 

[scootercat]

I've been a fabricator for over fourty years and the best thing to remember....Your cutting Metal,with Metal....So remove it in stages,drill a starter hole with a Center bit, on a good prick punched location Then on to a 3/16 carbide bit,into mild steel spun at 700 rpm....Then if Your going large say 1'' or 1.5"....jump to a 1/2" hss bit,spun at 500 rpm...Then on to a 3/4" hss run at 200 rpm,then to the 1" same speed and the the 1.5" same speed....Don't force it,let it cut....Small thin curls that are not BLUE...thats too hot/fast/force..All of the above is with lube of Your choice,I like Marvel Mistery Oil....Smells better than motor oil,works good too....Another thing,look at the angel of the tip, there are different angles for different materials...Most metal work in mild st. the bit are at a lesser angle than come on the big box stores bits,So Beware! ......Graingers/McMaster Carr sell the good ones....Scootercat....

 

[Bikerscum]

I've been a fabricator for over fourty years and the best thing to remember....Your cutting Metal,with Metal....So remove it in stages,drill a starter hole with a Center bit, on a good prick punched location Then on to a 3/16 carbide bit,into mild steel spun at 700 rpm....Then if Your going large say 1'' or 1.5"....jump to a 1/2" hss bit,spun at 500 rpm...Then on to a 3/4" hss run at 200 rpm,then to the 1" same speed and the the 1.5" same speed....Don't force it,let it cut....Small thin curls that are not BLUE...thats too hot/fast/force..All of the above is with lube of Your choice,I like Marvel Mistery Oil....Smells better than motor oil,works good too....Another thing,look at the angel of the tip, there are different angles for different materials...Most metal work in mild st. the bit are at a lesser angle than come on the big box stores bits,So Beware! ......Graingers/McMaster Carr sell the good ones....Scootercat....

What he said.

Although I think you can omit the carbide.

Here's THE BIGGEST F UP people do when drilling big holes...

You hear you need to drill it slow. Your drill runs 10,000 RPM so you figure 3000 is slow.

In the larger sizes, you should be able to count the rpms. Yeah, that slow.

 

[turftech 1]

Thanks everyone, I have learned tons. It seems my problem is more my technique than my drill bits. I have used water from time to time to cool the bit and the material, but not oil, and my RPMs have been way too high.

 

[george3]

as said low rpm, let the tool do the cutting minumal pressure. oil or tool cool helps. Just like sanding let the sand paper do the job.

 

[manco12]

I use a drill press and used motor oil. I have cheap bits that I couldn't do much with by hand but they still work beautifully in a drill press. Regardless of drill press or by hand, you do want to go slow. I like to drill larger holes at 200rpm in the drill press, the lower the better. HSS bits are good for hand drills because they are cheap and don't break too easily. You don't want to get expensive bits that should last long but don't if you just break or chip them. And if you don't have a good drill get one. You want a good powerful low speed drill.

 

[67tempest]

I agree with slow speed, even pressure and lots of oil. I've drilled 1" holes in 1" plate steel using a DC drill press that could be slowed down to less than 100 rpm. To high a speed just burns out your bit's and gets you nowhere.

 

[turftech 1]

Hey, you guys know your stuff!

Today I needed to drill several large holes into a 3/16" plate, I started small, used oil and used my drill press's slowest setting. Drilled all the holes without having to sharpen a single bit in between.

Thanks!:thumbsup:

 

[manco12]

Hey, you guys know your stuff!

Today I needed to drill several large holes into a 3/16" plate, I started small, used oil and used my drill press's slowest setting. Drilled all the holes without having to sharpen a single bit in between.

Thanks!:thumbsup:

motor oil? :laugh:

I swear that stuff works best for drilling holes. Thinner oils just don't seem to work well. And make sure it's synthetic oil. :laugh::laugh::laugh: joking, I know I'm not funny right now, I'm tired.